Micromagnetic analysis of magnetic after-effects in amorphous alloys by two-level systems

In amorphous ferromagnetic alloys relaxation effects influence all properties of the hysteresis loop. We have investigated with an AC technique (field amplitude
\mu_{o}\hat{H} \leq 0.25 \mu
T) the magnetic after-effect (MAE) of a nearly non magnetostrictive Co-alloy as well as of magnetostrictive Fe-alloys. On the assumption of thermally activated processes with Arrhenius equations
\tau = \tau_{o}.\exp[Q/kT]
, for the relaxation times τ, the time and temperature dependence of the MAE can be described by a spectrum of relaxation times. By means of a computer analysis the distribution functions, P(Q), of the activation energies were determined.